Hepatitis A disease following the implementation of universal vaccination: who is at risk?

The incidence of acute hepatitis A in Israel has decreased 25 folds in less than a decade, following the introduction of a two-dose universal toddler's hepatitis A immunization in July 1999. This retrospective study describes demographic data and behavioural determinants of hepatitis A patients following the implementation of a vaccination programme. All records of hepatitis A patients reported to the Ministry of Health during the years 2003 through 2005 were reviewed, and an epidemiological investigation was conducted. During the study period, 420 hepatitis A patients were reported, representing an average annual incidence of two per 100,000 population. Case fatality rate was 0.5%. The majority of the patients were younger than 15 years of age, males and non-Jewish. The highest incidence was recorded in east Jerusalem, where vaccine coverage is relatively low. After exclusion of 165 east Jerusalem patients, 133 (52.2%) patients were available for an interview. Of those, 16 (6%) had possible occupational exposure, 37 (27.8%) travelled to endemic areas, 44 (17%) were contacts of hepatitis A cases, and 3 male patients had sex with men. No known risk determinant was identified in 33 (24.8%) patients. Four patients (3%) were previously immunized with one dose, and none had two doses. The introduction of universal toddler hepatitis A vaccination decreased morbidity. Most of the patients who were detected 4-6 years after the implementation of the vaccination programme could be classified into one of the known risk groups for hepatitis A infection or living in a partly vaccinated community.